Thermostatically controlled switch



July 36, 19%., v. L. SHAW THERMQSTATICALLY CONTROLLED SWITCH Filed Jan. 21, 1939 "ulh l Patented July 30, 1940 UNITED STATES PATENT OFFICE Vincent L. Shaw, Evanston, Ill.

Application January 21, 1939, Serial No. 252,111

2 Claims.

My invention relates to thermostatically controlled plug switches.

One of the objects of my invention is to provide an improved thermostatically controlled snap plug switch for use with an electrical translating device, such as an electric iron.

A further object of my invention is to provide a thermostatically controlled switch in which the thermostat is prevented from releasing the switch to open by the presence of steam generated by th controlled translating device.

Further objects and advantages of the invention will be apparent from the description and claims.

In the drawing in which an embodiment of my invention is shown,

Figure 1 is a side elevational view with parts broken away, showing the plug switch in combination with an electric iron;

80 Fig. 2 is a face view of a portion of the switch casing and the parts mounted thereon;

Fig.3 is a section on the line 3-3 of Fig. 2; and

Fig. 4 is a face view of the cover section of the casing.

Referring to the drawing in detail, the construction shown comprises a steam electric iron I and a thermostatically controlled plug switch 2 for'shutting off the current to the iron in case of an excessive rise in temperature, such as might occur if no water is in the water reservoir of the iron. The steam electric iron comprises the twopart face plate 3 between the parts of which the heating element 4 is located, a cover or housing 35 portion 5 cooperating with the plate element to provide a water reservoir, a gasket 6 between the plate and cover, a handle I, a closure 8 for use in filling the water reservoir, a steam pipe. 9 leading from a point l0 above the liquid level in the reservoir to a point ll adjacent the point of the iron, and suitable contact blades or pins l2 (not shown) for engagement with the quick-detachable contacts l3 and ll of the plug switch. The lower portion of the front of the face plate may be provided with small openings If: for the escape of the steam generated by the heating element 4.

The plug switch shown comprises a housing of insulating material formed of two mating halvesone of which forms a cover portion l6 and the.

50 other of which forms a base portion I! on which the quick detachable contacts 13 and H, the wir ing terminals l8 and IS, the snap switch 20, and the thermostatically controlled latching means 2| are mounted. A pilot light 22 may be provided, if

i desired, which will be lit whenever current is flowing through the heating coils 4 of the electric iron: The quick detachable contacts l3 and It may be of any suitable construction located in recesses in the base portion of the plug. The wiring terminals l8 and H! are mounted in suitable recesses in the upper end of the plug switch. A conductor strip 23 may be provided between the binding terminal l8 and contact l3. The circuit between the other wiring terminal l9 and contact I4 is opened and closed by means of the snap switch 20. This snap switch comprises a manually operable member 24 pivoted at 25 and oscillatable back and forth, a U-shaped contact blade 26 pivotally mounted at 25 and oscillatable back and forth from the closed position shown in Fig. 2 to its open position, a switch blade biasing spring 21 having one end bearing on the cross piece of the oscillatable switch blade 26 and the other end bearing on a projection on the manually operable oscillatable. member 24. This switch blade actuating spring 21 is movable by the manually operable member 24 from a position in which it is biased to give a snap closing action to the switch blade to a position in which it is biased to give a snap opening movement of the switch blade. The switch blade 26 is movable from a position in which it electrically connects the contact 28 with the contact 29 to a position in which it breaks the circuit'between these contacts. The contact 29 is formed as part ofthe metallic strip 30 connected with the binding terminal l9 and the contact 28 is formed as part of a strip electrically connected with the quick detachable contact H. In order to hold the switch closed when moved to closed position, a latch member 2| is provided, pivotally mounted at 3| and biased toward latching position by means of a coil torsion spring 32. In order to return the manually operable actuating member 24 after it has been moved to closing position to a position in which the switch blade actuating spring 21 will be biased to open the switch, a coil torsion spring 33 is provided wrapped around the pivot pin 25 of the switch and having one end anchored to the oscillatable manually operable member 24 and the other end anchored to any suitable part of the casing. The pilot light 22 may have one terminal 34 connected with the metallic latch member at 35 and the other end connected by means of the conductor 36 with the quick detachable contact I3.

In order to release the latch when the temperature is excessive, a thermostatic element 31 is provided located in a recess in the base portion ll of the housing. This thermostatic element may be in the form of a two-leaf metallic memher, the leaves 01' which are caused to separate by a rise in temperature. As the temperature rises, the upper end of the leaf 38 will move away from the upper end of the other leaf 39 and will engage the tip of the latch 2| and will eventually free the detent on the latch from holding engagement I the thermostatic element 31, the screw may beprovided with a reduced extension ll extending loosely through openings in the leaves of the thermostatic element 31.

In order to assist in the transfer of heat from the electric iron to the thermostatic element, sheet metal conductors 42 and 43 may be provided between the thermostatic element and portions of the quick detachable contact It so that the thermostatic element 31 is in thermal conductivity relation with respect to the quick detachable contact l4. The quick detachable contact is, of course, in thermal conductivity relation with respect to the heating coils of the electric iron.

If for any reason the water in the reservoir should evaporate completely and the current remain on, the rise in temperature would soon cause the packing 6 between the lower edge of the cover 5 and the plate 3 to deteriorate to such an extent .that it could not be depended upon as a watertight packing.

, of the switch button returning spring 33. When the switch button is in the dotted-line position,

the switch blade 26 will have moved to the fullline position. where it .will be latched by the spring-pressed latch 2|. The return of the switch button to the full-line position shifts the switch bladebiasing spring 21 past the dead center position to a position in which it is biased to snap the switch to open position. The switch, however, is held against opening movement by the latch 2|. If, for any reason such as the evaporation of water in the reservoir, the temperature becomes excessive, the thermostatic element 31 will expand to shift the latch 2 l to releasing position, whereupon the switch blade biasing spring 21 will snap the switch to open position.

It will be seen that in the construction described the switch will move to closed position with a snap action and will move to open position with a snap action and that it is released for the snap opening action by a thermostatically controlled element. It will also be seen that in this construction when the switch is moved to closed position it will remain in closed position so long as steam is being generated by the controlled thermostatic device.

Further modifications will be apparent to those skilled in the art and it is desired, therefore, that the invention be limited only by the prior art and the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A plug switch for use with an electric translating device comprising quick detachable contacts for engagement with the contacts on the translating device, a quick make-and-break switch for controlling the circuit, and thermostatically controlled latching means for holding the switch in on position released by said thermostatic means, said switch comprising a manually operable member movable from one position to another, a switch-actuating spring which in one position of said manually operable member biases the switch to snap open and in the other position of the manually operable member biases the switch to snap closed, and a spring biasing said manually operable member toward the position in which the switch operating spring is biased to open theswitch whereby when the manually operable member is moved to close the switch and the switch is latched closed the thermostatically controlled latch means may unlatch the spring to enable the switch-actuating spring to snap the switch open.

2. A switch for use with an electric heating element comprising. contacts for electrical connection with the electric heating element, a

quick make-and-break switch for controlling the closed, and a spring biasing said manually operable member toward the position in which the switch operating spring is biased to open the switch whereby when the manually operable member is moved to close the switch and the switch is latched closed the thermostatically controlled latch means may unlatch the spring to enable the switch-actuating spring to'snap the switch open.

VINCENT L. SHAW. 

